Hold a match horizontally before a mirror. If the match’s head is to the right, then so is that of its reflection — the match is not reversed left to right. But now hold up the matchbox. Its writing is reversed. Why?

“Here is a related puzzle,” writes psychologist Richard Gregory in Mirrors in Mind (1997). “Hold a mug with writing on it to a mirror. What do you see in the mirror? The reflection of the handle is unchanged — but the writing is right-left reversed. Can a mirror read?!”

Set two mirrors together at a 60° angle and rotate the pair around your line of sight. Your image is preserved despite the mirrors’ rotation. This is not the case if the mirrors are set at 45° or 90°. Why?